Adhesive article comprising an acrylic foam layer

ABSTRACT

The present disclosure provides an adhesive article comprising a foam layer having first and second major sides and a pressure sensitive adhesive layer associated with at least one of the major sides for the foam layer, said pressure sensitive adhesive layer comprising a cross-linked rubber and wherein the foam layer comprises an acrylic polymer obtainable by polymerization a polymerizable composition comprising one or more alkyl acrylates having an average of 3 to 14 carbon atoms in the alkyl groups, one or more polar monomers and one or more multi-functional monomers having at least two free radical polymerizable groups.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2010/025045, filed Feb. 23, 2010, which claims priority to EPApplication No. 09154408.0, filed Mar. 5, 2009, the disclosure of whichis incorporated by reference in its/their entirety herein.

FIELD

The present disclosure relates to an adhesive article comprising anacrylic foam layer and a pressure sensitive adhesive layer thatcomprises a cross-linked rubber. The disclosure further relates tomaking the adhesive article and use thereof.

BACKGROUND

Adhesives and tapes are commonly used to bond two substrates together toform a bonded composite. Particular adhesive tapes include those thathave a foam layer. Such tapes or adhesive articles are used for examplein the automotive industry where they may be employed to bond variouscomponents to the body of a car or other motor vehicle. Typically theyare used to bond such parts as emblems, plastic parts as well as rubbergaskets to doors.

Examples of adhesive tapes are disclosed in for example WO 2008/070386,U.S. Pat. No. 6,503,621 and U.S. Pat. No. 4,415,615.

While a vast array of adhesives and tapes are available, advances insubstrates and end use requirements continues to drive a need for newadhesive formulations and tape constructions. For example, developmentsin paints and coatings on automotive parts to which the adhesive tapesare to be bonded have proven to be particularly challenging. Typically,these coatings and paints have low surface energy, requiring thedevelopment of special adhesive tapes. Likewise, there is a continuingtrend in the transportation sector and in particular in the automotiveindustry to further reduce weight of for example cars in order to saveon fuel consumption. This trend is leading to use and application ofadhesive tapes where they have previously not been used or to theapplication of tapes in new configurations that are more demanding forexample in stress-strain to which the adhesive tape may be subjected. Inaddition to performance properties, environmental regulations andprocessing costs also influence product formulation requirements.

It would thus be desirable to find further adhesive articles that haveone or more improved performance properties. For example, it would bedesirable to find an adhesive article that has improved adhesiveperformance in adhering to low energy surfaces such as for example paintand coating surfaces of automotive parts. It would furthermore bedesirable to find adhesive articles that can be readily manufactured inan economical and cost effective way. Yet further, it would be desirableto find adhesive articles that have good environmental properties. Also,adhesive articles that are compatible with existing manufacturingmethods that employ adhesive articles would be desirable.

SUMMARY

In one aspect, the present disclosure provides an adhesive articlecomprising a foam layer having first and second major sides and apressure sensitive adhesive layer associated with at least one of themajor sides for the foam layer, said pressure sensitive adhesive layercomprising a cross-linked rubber and wherein the foam layer comprises anacrylic polymer obtainable by polymerization a polymerizable compositioncomprising one or more alkyl acrylates having an average of 3 to 14carbon atoms in the alkyl groups, one or more polar monomers and one ormore multi-functional monomers having at least two free radicalpolymerizable groups.

The term “associated with” as used in connection with the presentdisclosure means that the relevant layer is provided directly on thesurface or indirectly through the intermediary of one or more layerssuch as primer layers for example.

It has been found that that the adhesive articles show good to excellentadhesive performance. For example, they may provide good or excellentadhesive performance to low energy surface, including good 90° peeladhesion performance as well as performance under static and dynamicshear testing.

In a further aspect of the present disclosure, there is provided amethod of making the adhesive article comprising:

-   -   (i) making a foam layer having first and second major sides        by (a) providing a polymerizable composition comprising one or        more alkyl acrylates having an average of 3 to 14 carbon atoms        in the alkyl groups, one or more polar monomers and one or more        multi-functional monomers having at least two free radical        polymerizable groups, (b) frothing said polymerizable        composition and (c) polymerizing said polymerizable composition;    -   (ii) applying a pressure sensitive adhesive composition        comprising a cross-linkable rubber on one or both of said first        and second major sides of said foam layer so as to form a        pressure sensitive adhesive layer; and    -   (iii) cross-linking said cross-linkable rubber.

DETAILED DESCRIPTION

In yet a further aspect, the present disclosure provides a use of theadhesive article comprising adhering the adhesive article to a substratethrough said pressure sensitive adhesive layer.

Particular embodiments of the present disclosure are summarized asfollows:

-   1. Adhesive article comprising a foam layer having first and second    major sides and a pressure sensitive adhesive layer associated with    at least one of the major sides for the foam layer, said pressure    sensitive adhesive layer comprising a cross-linked rubber and    wherein the foam layer comprises an acrylic polymer obtainable by    polymerization a polymerizable composition comprising one or more    alkyl acrylates having an average of 3 to 14 carbon atoms in the    alkyl groups, one or more polar monomers and one or more    multi-functional monomers having at least two free radical    polymerizable groups.-   2. Adhesive article according to embodiment 1 wherein said    polymerizable composition comprises 83 to 97% by weight of said    alkyl acrylates, 3 to 16% by weight of said polar monomers and 0.01    to 1% by weight of said multi-functional monomers.-   3. Adhesive article according to embodiment 1 or 2 wherein said foam    layer further comprises a thixotropic agent.-   4. Adhesive article according to embodiment 3 wherein said    thixotropic agent comprises fumed silica.-   5. Adhesive article according to any of the previous embodiments    wherein said foam layer comprises a frothed foam.-   6. Adhesive article according to any of the previous embodiments    wherein said pressure sensitive adhesive layer comprises an acrylic    pressure sensitive adhesive component.-   7. Adhesive article according to embodiment 6 wherein said acrylic    pressure sensitive adhesive component comprises an acrylic polymer    having repeating units derived from one or more alkyl acrylates    having 3 to 14 carbon atoms in the alkyl group and one or more polar    monomers.-   8. Adhesive article according to any of the previous embodiments    wherein said polar monomers are selected from the group consisting    of acrylic acids, itaconic acid, acrylamides, acrylonitrile,    N-vinylpyrrolidone, N-vinyl caprolactam and combinations thereof-   9. Adhesive article according to any of the previous embodiments    wherein cross-linked rubber comprises a cross-linked block copolymer    having a rubbery block and a glassy block.-   10. Adhesive article according to embodiment 9 wherein said rubbery    block comprises a first polymerized conjugated diene, a hydrogenated    derivative thereof, or combinations thereof and wherein said glassy    block comprises a monovinyl aromatic monomer.-   11. Adhesive article according to embodiment 9 or 10 wherein said    pressure sensitive adhesive layer comprises 30 to 50 parts by weight    based on the total weight of the pressure sensitive adhesive layer,    of said block copolymer and from 0.1 to 10 parts by weight based on    the total weight of the pressure sensitive adhesive layer, of said    acrylic pressure sensitive adhesive component.-   12. Adhesive article according to embodiment 9 or 10 wherein said    pressure sensitive adhesive layer comprises 10 to 20 parts by weight    based on the total weight of the pressure sensitive adhesive layer,    of said block copolymer and from 40 to 60 parts by weight based on    the total weight of the pressure sensitive adhesive layer, of said    acrylic pressure sensitive adhesive component.-   13. Adhesive article according to any of the previous embodiments    wherein each of said first and second major side of said adhesive    article have associated with them said pressure sensitive adhesive    layer.-   14. Adhesive article according to any of embodiments 1 to 12 wherein    said adhesive article has said pressure sensitive adhesive layer    associated with said first major side and wherein said second major    side does not have an adhesive layer associated with it.-   15. Adhesive article according to any of embodiments 1 to 12 wherein    said adhesive article has said pressure sensitive adhesive layer    associated with said first major side and wherein said second major    side has a further adhesive layer associated with it.-   16. Adhesive article according to embodiment 13 wherein said further    adhesive layer comprises a pressure sensitive adhesive component or    a heat activatable adhesive component.-   17. Adhesive article according to any of the previous embodiments    wherein the thickness of said foam layer is between 0.3 mm and 2 mm    and wherein the weight per area of said pressure sensitive adhesive    layer is between 40 g/m² and 100 g/m².-   18. Method of making an adhesive article as embodimented in any of    embodiments 1 to 17 comprising:    -   (i) making a foam layer having first and second major sides        by (a) providing a polymerizable composition comprising one or        more alkyl acrylates having an average of 3 to 14 carbon atoms        in the alkyl groups, one or more polar monomers and one or more        multi-functional monomers having at least two free radical        polymerizable groups, (b) frothing said polymerizable        composition and (c) polymerizing said polymerizable composition;    -   (ii) applying a pressure sensitive adhesive composition        comprising a cross-linkable rubber on one or both of said first        and second major sides of said foam layer so as to form a        pressure sensitive adhesive layer; and    -   (iii) cross-linking said cross-linkable rubber.-   19. Method according to embodiment 18 wherein said cross-linking    comprises exposing said cross-linkable rubber to e-beam radiation.-   20. Method according to embodiment 19 wherein said pressure    sensitive adhesive composition is provided directly onto said foam    layer and wherein said e-beam is focused at or in the proximity of    an interface defined between said foam layer and said pressure    sensitive adhesive composition.-   21. Method according to any of embodiments 18 to 20 wherein said    polymerizable composition comprises a UV-photosensitive initiator    and wherein said polymerizable composition is exposed to UV-light.-   22. Method according to any of embodiments 18 to 21 wherein said    frothing is carried out prior to or simultaneous with said    polymerization.-   23. Method according to any of embodiments 18 to 22 wherein said    frothing is carried out by whipping the polymerizable composition    with an inert gas.-   24. Use of an adhesive article according to any of embodiments 1 to    17 comprising adhering said adhesive article to a substrate through    said pressure sensitive adhesive layer.-   25. Use of an adhesive article according to embodiment 24 wherein    said substrate has a surface having a surface energy of less than 45    dynes/cm and said adhesive article is adhered to said surface    through said pressure sensitive adhesive layer.-   26. Use of an adhesive article according to any of embodiments 24 or    25 wherein said adhesive article comprises a further adhesive layer    on a major side opposite to the side comprising the pressure    sensitive adhesive layer and wherein said adhesive article is    adhered to a rubber gasket through said further adhesive layer.

DEFINITIONS

In the disclosure of the present application the following terms aredefined as follows unless otherwise indicated:

“acrylic” is used to identify both acrylic as well as methacrylicmonomers and polymers.

“mono-functional monomer” means a monomer having only one polymerizablegroup.

“multi-functional monomer” means a monomer having two or morepolymerizable groups.

Any ranges identified in the present application are to be understood asincluding the end points unless expressly stated otherwise.

The term “pressure sensitive adhesive” is used to indicate materialsthat materials

(e.g., elastomers) that are either inherently tacky or that have beentackified with the addition of tackifying resins. Pressure sensitiveadhesives according to the present disclosure include those that can beidentified by any of the known methods for identifying pressuresensitive adhesives and include in particular those that can beidentified by one or more of the following methods. According to a firstmethod, pressure sensitive adhesives may be defined by the Dahlquistcriteria described in Handbook of Pressure Sensitive AdhesiveTechnology, D. Satas, 2nd ed., page 172 (1989) at use temperatures. Thiscriterion defines a good pressure sensitive adhesive as one having a 1second creep compliance of greater than 1×10⁻⁶ cm²/dyne. Alternatively,since modulus is, to a first approximation, the inverse of compliance,pressure sensitive adhesives may be defined as adhesives having amodulus of less than 1×10⁶ dynes/cm².

Another method of identifying a pressure sensitive adhesive is that itis aggressively and permanently tacky at room temperature and firmlyadheres to a variety of dissimilar surfaces upon mere contact withoutthe need of more than finger or hand pressure as described in “Glossaryof Terms Used in the Pressure Sensitive Tape Industry” provided by thePressure Sensitive Tape Council, August, 1985.

Another suitable method of identifying a pressure sensitive adhesive isthat it preferably has a room temperature storage modulus within thearea defined by the following points as plotted on a graph of modulusversus frequency at 25° C.: a range of moduli from approximately 2×10⁵to 4×10⁵ dynes/cm² at a frequency of approximately 0.1 radian/second(0.017 Hz), and a range of moduli from approximately 2×10⁶ to 8×10⁶dynes/cm² at a frequency of approximately 100 radians/second (17 Hz)(for example, see FIG. 8-16 on p. 173 Handbook of Pressure SensitiveAdhesive Technology, D. Satas, 2nd ed., (1989)).

In the following, the invention will be described in more detail withreference to particular embodiments without however the intention tolimit the invention.

The adhesive article comprises a foam layer having an acrylic polymerobtainable by polymerization of a polymerizable composition comprisingone or more alkyl acrylates having an average of 3 to 14 carbon atoms inthe alkyl group, one or more polar monomers and one or moremulti-functional monomers having at least two free radical polymerizablegroups.

The one or more alkyl acrylates of the polymerizable composition aretypically mono-functional monomers and include in particular acrylicacid ester of a nontertiary alcohol in which the alkyl group contains atleast about 3 carbon atoms (on average), and preferably about 4 to about14 carbon atoms (on average). Typically, the homopolymers of suchmonomers have a Tg of no greater than about 0° C. Examples of classes ofsuitable acrylic acid esters include, but are not limited to,2-methylbutyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, laurylacrylate, n-decyl acrylate, 4-methyl-2-pentyl acrylate, isoamylacrylate, sec-butyl acrylate, and isononyl acrylate. Preferred acrylicacid esters that can be used include, but are not limited to,2-ethylhexyl acrylate, isooctyl acrylate, lauryl acrylate, and2-methylbutyl acrylate. Various combinations of such monomers can beemployed. For example, a combination of two or more alkyl acrylates maybe used such as a combination of 2-ethylhexyl acrylate and isooctylacrylate.

The polymerizable composition further includes one or more polarmonomers, typically monofunctional polar monomers. Examples thereofinclude in particular acidic monomers such as carboxylic acid monomersas well as various acrylamides. Particular examples of polar monomersinclude acrylic acid, methacrylic acid, itaconic acid, maleic acid,fumaric acid, 2-hydroxyethyl acrylate or methacrylate, N-vinylpyrrolidone, N-vinyl caprolactam, acrylamide, methacrylamide,N-substituted and N,N-disubstituted acrylamides such as N-ethylacrylamide, N-hydroxyethyl acrylamide, N,N-dimethyl acrylamide,N,N-diethyl acrylamide, and N-ethyl, N-dihydroxyethyl acrylamide,acrylonitrile, methacrylonitrile and maleic anhydride. Preferred polarmonomers include, but are not limited to, acrylic acid, itaconic acid,N,N-dimethyl acrylamide, acryl amide, N-vinyl pyrrolidone and N-vinylcaprolactam. Various combinations of such polar monomers can be employedand in a particular embodiment a combination of two or more polarmonomers is contemplated such as for example a combination of acrylicacid and itaconic acid.

The polymerizable composition from which the acrylic polymer of the foamlayer can be derived further includes one or more multi-functionalmonomers that have two or more ethylenically unsaturated groups.Examples of multi-functional monomers include in particularmulti-functional acrylic monomers but other multi-functional monomerssuch as butadiene and substituted triazines such asvinyl-halomethyl-s-triazine type compounds such as for example2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine. Preferred arepolyacrylic-functional monomers such as, for example, pentaerythritoltetraacrylate, tripropyleneglycoldiacrylate, 1,12-dodecanedioldiacrylate. Particular preferred examples of multi-functional acrylicmonomers include 1,2 ethylene glycol diacrylate, hexane diol diacrylateand trimethylol propane triacrylate.

The acrylic polymer of the foam layer is typically obtainable from apolymerizable composition having a major amount of the one or more alkylacrylates, for example at least 84% by weight (based on the total weightof monomers in the composition). A typical range is from 84 to 97% byweight or from 88 to 94% by weight. The amount of multi-functionalmonomer or monomers in the polymerizable composition is typically atleast 0.01% by weight and may range for example from 0.01% by weight to1% or less by weight of the total weight of monomers in the compositionor for example from 0.1 to 0.5% by weight. The polar monomer or monomersare typically present in amount of at least 3% by weight of the totalweight of monomers in the composition, an exemplary range being from 3to 16% or from 5 to 12% by weight.

The polymerizable composition may contain further components includingin particular a thixotropic agent. Examples of thixotropic agentsinclude fumed silica. The polymerizable composition may also containmicrosphere such as for example hollow glass bubbles or polymericmicrospheres. Furthermore, it may be desirable to include a surfactantin the polymerizable composition. Tackifiers, in particular tackifierssuitable for use with acrylic adhesives may be added as well. Examplesthereof include in particular rosin esters, aromatic resins, aliphaticresins, terpenes and partially hydrogenated and hydrogenated resins.

The polymerizable composition typically also includes an initiator forinitiating a free radical polymerization including thermal as well asphoto-initiators. Photoinitiators are preferred for use in connectionwith this disclosure. Examples of initiators can be found in U.S. Pat.No. 4,181,752 (Martens et al.), U.S. Pat. No. 4,833,179 (Young et al.),U.S. Pat. No. 5,804,610 (Hamer et al.), U.S. Pat. No. 5,382,451 (Johnsonet al.), U.S. Pat. No. 4,619,979 (Kotnour et al.), U.S. Pat. No.4,843,134 (Kotnour et al.), and U.S. Pat. No. 5,637,646 (Ellis). Aparticular example includes 2,2 dimethoxy-2-phenylacetophenone.

The foam layer of the adhesive article will typically have a thicknessof at least 0.3 mm, for example at least 0.5 mm. A typical thicknessrange for the foam layer is from 0.3 mm up to 2 mm, for example from 0.5mm up to 1.5 mm or from 0.7 mm to 1.2 mm. The foam layer typically has acellular membrane structure which may have 15 to 85% of voids.

The foam layer is typically obtained and produced according to themethods described in U.S. Pat. No. 4,415,615. The process typicallycomprises frothing the polymerizable composition, coating the froth on abacking such as for example a release liner and polymerizing thepolymerizable composition.

Frothing is conveniently accomplished by whipping a gas into thepolymerizable composition. Useful frothing gases typically are inert andinclude nitrogen gas or carbon dioxide. In a particular embodiment, themonomers of the polymerizable composition may be partially polymerizedprior to frothing so as to achieve a desirable viscosity for thefrothing step. Useful viscosities to froth a composition are typicallybetween 1000 and 40,0000 cps. The viscosity is typically selected so asto achieve a desired cell uniformity. For example, above 5000 cps, ahigher cell uniformity will typically be obtained.

Additionally and alternatively to using prepolymerization to achieve adesired viscosity, a thixotropic agent such as fumed silica may be used.In such case, polymerization may be carried out in one step.

Polymerization of the polymerizable composition may be carried out byheat activation but is preferably is photoinitiated and hence thepolymerizable composition will typically contain a photoinitiator.Typically, photoinitiation is carried out by UV irradiation and a UVinitiator will be used. If the polymerization is carried out in twosteps (in case of pre-polymerization to enable a suitable viscosity asdescribed above), the amount of photo-initiator initially used may beenough to allow initiation of further polymerization. Typically however,a further addition of photoinitiator may be desired to initiate furtherpolymerization following frothing.

When the polymerization is to be effected by ultraviolet radiation, thepolymerizable coating is preferably protected from air by a plastic filmoverlay which is fairly transparent to ultraviolet radiation and has alow-adhesion surface. Biaxially-oriented polyethylene terephthalate filmwhich is about 75% transparent to ultraviolet radiation is very useful.If the underlying backing also has a low-adhesion surface, both thebacking and the transparent plastic film can be stripped away so thatthe cellular adhesive membrane may be used for mounting objects. Forsuch use, the cellular membrane may be reinforced by a tissue-like webto avoid becoming distorted if it is to be removed from both the backingand the transparent overlay before being applied.

If instead of covering the polymerizable coating, the polymerization isto be carried out in an inert atmosphere, the permissible oxygen contentof the inert atmosphere can be increased by mixing into thepolymerizable composition an oxidizable tin compound as taught in U.S.Pat. No. 4,303,485 (Levens), which also teaches that by doing so, thickcoatings can be polymerized in air.

Regardless of the process by which the cellular structure of theadhesive membrane is created, it is preferred to include a surfactant inthe composition, preferably a silicone or a fluorochemical known to beuseful for foaming organic liquids that have low surface tension. Bydoing so, foams with cellular adhesive membranes of good uniformity canbe produced wherein the cells have an average diameter within the rangeof 0.05 to 0.3 mm. Typically, 90% of the cells of the adhesive membranevary in size no more than 2:1, but some of the adhesive membranes havebeen characterized by significant variations in cell size.

On one or both opposite major sides of the foam layer is provided apressure sensitive adhesive layer (also called skin layer) thatcomprises a cross-linked rubber. The cross-linked rubber may be obtainedfrom crosslinking, typically through e-beam, of a cross-linkable blockcopolymer that has a rubbery block and a glassy block. Generally, arubbery block exhibits a glass transition temperature (Tg) of less thanroom temperature. In some embodiments, the Tg of the rubbery block isless than about 0° C., or even less than about −10° C. In someembodiments, the Tg of the rubbery block is less than about −40° C., oreven less than about −60° C.

Generally, a glassy block exhibits a Tg of greater than roomtemperature. In some embodiments, the Tg of the glassy block is at leastabout 40° C., at least about 60° C., at least about 80° C., or even atleast about 100° C.

A suitable block copolymer includes one or more a rubbery blocks, R, andone or more glassy blocks, G. In some embodiments, the block copolymercomprises at least three glassy blocks. In some embodiments, the blockcopolymer comprises between three and five glassy blocks, inclusive. Insome embodiments, the block copolymer comprises four glassy blocks.

In some embodiments, the block copolymer is a multi-arm block copolymerhaving the general formula Q_(n)-Y, wherein Q represents an arm of themulti-arm block copolymer; n represents the number of arms and is awhole number of at least 3; and Y is the residue of a multifunctionalcoupling agent. Each arm, Q, independently has the formula R-G, whereinG represents the glassy block; and R represents the rubbery block.

In some embodiments, the rubbery block comprises a polymerizedconjugated diene, a hydrogenated derivative of a polymerized conjugateddiene, or combinations thereof. In some embodiments, the conjugateddienes comprise 4 to 12 carbon atoms. Exemplary conjugated dienesinclude butadiene, isoprene, ethylbutadiene, phenylbutadiene,piperylene, pentadiene, hexadiene, ethylhexadiene, anddimethylbutadiene. The polymerized conjugated dienes may be usedindividually or as copolymers with each other. In some embodiments, theconjugated diene is selected from the group consisting of isoprene,butadiene, ethylene butadiene copolymers, and combinations thereof.

In some embodiments, at least one glassy block comprises a polymerizedmonovinyl aromatic monomer. In some embodiments, both glassy blocks of atriblock copolymer comprise a polymerized monovinyl aromatic monomer. Insome embodiments, the monovinyl aromatic monomers comprise 8 to 18carbon atoms. Exemplary monovinyl aromatic monomers include styrene,vinylpyridine, vinyl toluene, alpha-methyl styrene, methyl styrene,dimethylstyrene, ethylstyrene, diethyl styrene, t-butylstyrene,di-n-butylstyrene, isopropylstyrene, other alkylated-styrenes, styreneanalogs, and styrene homologs. In some embodiments, the monovinylaromatic monomer is selected from the group consisting of styrene,styrene-compatible monomers or monomer blends, and combinations thereof.

As used herein, “styrene-compatible monomers or monomer blends” refersto a monomer or blend of monomers, which may be polymerized orcopolymerized, that preferentially associate with polystyrene or withthe polystyrene endblocks of a block copolymer. The compatibility canarise from actual copolymerization with monomeric styrene; solubility ofthe compatible monomer or blend, or polymerized monomer or blend in thepolystyrene phase during hot melt or solvent processing; or associationof the monomer or blend with the styrene-rich phase domain on standingafter processing.

In the general formula for some multi-arm block copolymers of thepresent disclosure, Q_(n)-Y, n represents the number of arms and is awhole number of at least 3, i.e., the multi-arm block copolymer is astar block copolymer. In some embodiments, n is ranges from 3-10. Insome embodiments, n ranges from 3-5. In some embodiments, n is 4. Insome embodiments, n is equal to 6 or more.

In some embodiments, the first block copolymer is a polymodal blockcopolymer. As used herein, the term “polymodal” means that the copolymercomprises glassy blocks having at least two different molecular weights.Such a block copolymer may also be characterized as having at least one“high” molecular weight glassy block, and at least one “low” molecularweight glassy block, wherein the terms high and low are used relative toeach other. In some embodiments the ratio of the number averagemolecular weight of the high molecular weight glassy block, (Mn)_(H),relative to the number average molecular weight of the low molecularweight glassy block, (Mn)_(L), is at least about 1.25.

In some embodiments, (Mn)_(H) ranges from about 5,000 to about 50,000g/mol. In some embodiments, (Mn)_(H) is at least about 8,000, and insome embodiments at least about 10,000. In some embodiments, (Mn)_(H) isno greater than about 35,000 g/mol. In some embodiments, (Mn)_(L) rangesfrom about 1,000 to about 10,000 g/mol. In some embodiments, (Mn)_(L) isat least about 2,000, and, in some embodiments, at least about 4,000. Insome embodiments, (Mn)_(L) is less than about 9,000 g/mol, and, in someembodiments, less than about 8,000 g/mol.

In some embodiments, the first block copolymer is an asymmetric blockcopolymer. As used herein, the term “asymmetric” means that the arms ofthe block copolymer are not all identical. Generally, a polymodal blockcopolymer is an asymmetric block copolymer (i.e., a polymodal asymmetricblock copolymer) as not all arms of a polymodal block copolymer areidentical since the molecular weights of the glassy blocks are not allthe same. In some embodiments, the block copolymers of the presentdisclosure are polymodal, asymmetric block copolymers. Methods of makingasymmetric, polymodal block copolymers are described in, e.g., U.S. Pat.No. 5,296,547.

Generally, the multifunctional coupling agent may be any polyalkenylcoupling agent or other material known to have functional groups thatcan react with carbanions of the living polymer to form linked polymers.The polyalkenyl coupling agent may be aliphatic, aromatic, orheterocyclic. Exemplary aliphatic polyalkenyl coupling agents includepolyvinyl and polyalkyl acetylenes, diacetylenes, phosphates,phosphites, and dimethacrylates (e.g., ethylene dimethacrylate).Exemplary aromatic polyalkenyl coupling agents include polyvinylbenzene, polyvinyl toluene, polyvinyl xylene, polyvinyl anthracene,polyvinyl naphthalene, and divinyldurene. Exemplary polyvinyl groupsinclude divinyl, trivinyl, and tetravinyl groups. In some embodiments,divinylbenzene (DVB) may be used, and may include o-divinyl benzene,m-divinyl benzene, p-divinyl benzene, and mixtures thereof. Exemplaryheterocyclic polyalkenyl coupling agents include divinyl pyridine, anddivinyl thiophene. Other exemplary multifunctional coupling agentsinclude silicon halides, polyepoxides, polyisocyanates, polyketones,polyanhydrides, and dicarboxylic acid esters.

Still further, the cross-linked rubber of the pressure sensitiveadhesive layer may be obtained from the cross-linking of a linear blockcopolymer of the formulaR-(G)_(m)wherein R represents a rubbery block, G represents a glassy block, andm, the number of glassy blocks, is 1 or 2. In some embodiments, m isone, and the linear block copolymer is a diblock copolymer comprisingone rubbery block and one glassy block. In some embodiments, m is two,and the linear block copolymer comprises two glassy endblocks and onerubbery midblock, i.e., the linear block copolymer is a triblockcopolymer.

In some embodiments, the rubbery block of the linear block copolymercomprises a polymerized conjugated diene, a hydrogenated derivativethereof, or combinations thereof. In some embodiments, the conjugateddienes comprise 4 to 12 carbon atoms. Exemplary conjugated dienes usefulin the second block copolymer include any of the exemplary conjugateddienes described above.

In some embodiments, at least one glassy block, and in some embodiments,each glassy block of the linear block copolymer comprises a polymerizedmonovinyl aromatic monomer. In some embodiments, the monovinyl aromaticmonomers comprise 8 to 18 carbon atoms. Exemplary polymerized monovinylaromatic monomers useful in the second block copolymer include any ofthe exemplary polymerized monovinyl aromatic monomer, as describedabove.

In a particular embodiment a mixture of the linear block copolymer andthe aforementioned and described multi-arm block copolymer is used toobtain the cross-linked rubber of the pressure sensitive adhesive layer.In some embodiments, the ratio of multi-arm block copolymers to linearblock copolymers ranges from 1.5:1 to 9:1. In some embodiments, theratio of multi-arm block copolymers to linear block copolymer is atleast 1.85:1, or even at least 3:1. In some embodiments, the ratio ofmulti-arm block copolymers to linear block copolymers is no greater than5.7:1, or even no greater than 4:1.

The pressure sensitive adhesive layer in a particular embodiment furtherincludes one or more tackifiers and optionally one or more plasticizers.Generally, a tackifier will be selected to be compatible with a rubberyblock of a block copolymer as may be used for obtaining the cross-linkedrubber. As used herein, a tackifier is “compatible” with a block if itis miscible with that block. Generally, the miscibility of a tackifierwith a block can be determined by measuring the effect of the tackifieron the Tg of that block. If a tackifier is miscible with a block it willalter (e.g., increase) the Tg of that block.

A tackifier is “primarily compatible” with a block if it is at leastmiscible with that block, although it may also be miscible with otherblocks. For example, a tackifier that is primarily compatible with arubbery block will be miscible with the rubbery block, but may also bemiscible with a glassy block.

Generally, resins having relatively low solubility parameters tend toassociate with the rubbery blocks; however, their solubility in theglassy blocks tends to increase as the molecular weights or softeningpoints of these resins are lowered. Exemplary tackifiers that areprimarily compatible with the rubbery blocks include polymeric terpenes,hetero-functional terpenes, coumarone-indene resins, esters of rosinacids, disproportionated rosin acid esters, hydrogenated rosin acids, C5aliphatic resins, C9 hydrogenated aromatic resins, C5/C9aliphatic/aromatic resins, dicyclopentadiene resins, hydrogenatedhydrocarbon resins arising from C5/C9 and dicyclopentadiene precursors,hydrogenated styrene monomer resins, and blends thereof.

In particular embodiments, a first high Tg tackifier having a glasstransition temperature (Tg) of at least 60 degrees Celsius (° C.). Asused herein, the terms “high glass transition temperature tackifier” and“high Tg tackifier” refers to a tackifier having a glass transitiontemperature of at least 60° C. In some embodiments, the first high Tgtackifier has a Tg of at least 65° C., or even at least 70° C. In someembodiments, the first high Tg tackifier has a softening point of atleast about 115° C., and, in some embodiments, at least about 120° C.

In some embodiments, the block copolymer adhesive compositions include asecond high Tg tackifier that is primarily compatible with the glassyblock(s) of the multi-arm block copolymer and, optionally, with theglassy block(s) of the linear block copolymer. Generally, a tackifierthat is primarily compatible with a glassy block is miscible with theglassy block and may be miscible with a rubbery block.

Generally, resins having relatively high solubility parameters tend toassociate with the glassy blocks; however, their solubility in therubbery blocks tends to increase as the molecular weights or softeningpoints of these resins are lowered. Exemplary tackifiers that areprimarily compatible with the glassy blocks include coumarone-indeneresins, rosin acids, esters of rosin acids, disproportionated rosin acidesters, C9 aromatics, alpha-methyl styrene, C9/C5 aromatic-modifiedaliphatic hydrocarbons, and blends thereof.

In some embodiments, the pressure sensitive adhesive layer furthercomprises at least one component selected from the group consisting of alow Tg tackifier, a plasticizer, and combinations thereof. As usedherein, the term “low glass transition temperature tackifier” refers toa tackifier having a glass transition temperature of less than 60° C.Exemplary low Tg tackifiers include polybutenes.

Generally, a plasticizer is compatible with one or more blocks of thelinear block copolymer, and/or one or more blocks of the multi-arm blockcopolymer. Generally, a plasticizer that is compatible with a block willbe miscible with that block and will lower the Tg of that block.Exemplary plasticizers include naphthenic oils, liquid polybuteneresins, polyisobutylene resins, and liquid isoprene polymers.

In some embodiments, the ratio of the total amount of high glasstransition temperature tackifiers to block copolymers ranges from 0.8:1to 1.25:1. In some embodiments, the ratio of the total amount of high Tgtackifiers to block copolymers is at least 0.85:1, or even at least0.9:1. In some embodiments, the ratio of the total amount of high Tgtackifiers to block copolymers is no greater than 1.15:1, or even nogreater that 1.1 to 1.

In some embodiments, the ratio of the rubbery block compatible high Tgtackifier to the glassy block compatible high Tg tackifier is rangesfrom 1:1 to 9:1. In some embodiments, the ratio of the rubbery blockcompatible high Tg tackifier to the glassy block compatible high Tgtackifier is at least 1.25:1, or even at least 1.5:1. In someembodiments the ratio of the rubbery block compatible high Tg tackifierto the glassy block compatible high Tg tackifier is no greater than 4:1,or even no greater than 3:1.

In a particularly preferred embodiment, the pressure sensitive adhesivelayer also includes an acrylic pressure sensitive adhesive component.Typically, the pressure sensitive adhesive layer comprises at leastabout 0.1 parts, in some embodiments, at least about 0.5 parts, at leastabout 1 part, or even at least about 2 parts of an acrylic pressuresensitive adhesive component.

In a particular embodiment, the pressure sensitive adhesive layercomprise no greater than about 10 parts, in some embodiments, no greaterthan about 8 parts, no greater than about 5 parts, or even no greaterthan about 4 parts of the acrylic pressure sensitive adhesive component.The amount of cross-linked block copolymer will typically be between 30and 60 or between 30 and 50 parts by weight of the total weight of thepressure sensitive adhesive layer.

In another embodiment, the acrylic pressure sensitive adhesive componentmay be comprised in the pressure sensitive adhesive layer in an amountof between 40 and 60 parts by weight. In this embodiment, the amount ofcross-linked block copolymer will typically be between 10 and 20 partsby weight of the weight of the pressure sensitive adhesive layer.

Typically, the acrylic pressure sensitive adhesive component of thepressure sensitive adhesive layer is an acrylic polymer derived from oneor more acrylic esters of a non-tertiary alkyl alcohol that contains 3to 14 carbon atoms. Exemplary acrylic acid esters include isooctylacrylate, 2-ethylhexyl acrylate, butyl acrylate, isobornyl acrylate, andcombinations thereof. Exemplary methacrylic acid esters include themethacrylate analogues of these acrylic acid esters. Typically, theacrylic polymer will further comprises one or more units derived from apolar monomer such as for example described above.

In some embodiments, the acrylic polymer comprises at least about 70parts, in some embodiments, at least about 80 parts, at least about 90parts, at least about 95 parts, or even about 100 parts of at least oneacrylic or methacrylic ester of a non-tertiary alkyl alcohol. In someembodiments, acrylic polymer comprises no greater than about 30 parts,in some embodiments, no greater than about 20 parts, no greater thanabout 10 parts, no greater than about 5 parts, and even no greater than1 part of at least one copolymerized polar monomer. In some embodiments,the acrylic adhesive composition does not include a copolymerized polarmonomer.

In some embodiments, the ratio of the combination of the blockcopolymers and high Tg tackifiers to the acrylic pressure sensitiveadhesive component is at least 8.3:1. In some embodiments, the ratio ofthe combination of the block copolymers and high Tg tackifiers to theacrylic pressure sensitive adhesive component is at least 12.5:1, atleast 22:1, at least 90:1, or even at least 180:1.

In some embodiments, the ratio of the combination of the blockcopolymers, high Tg tackifiers, and acrylic pressure sensitive adhesivecomponent to the liquid plasticizer ranges from 32:1 to 10:1. In someembodiments, the ratio of the combination of the block copolymers, highTg tackifiers, and acrylic pressure sensitive adhesive component to theliquid plasticizer is no great than 25:1, or even no greater than 20:1.In some embodiments, the ratio of the combination of the blockcopolymers, high Tg tackifiers, and acrylic pressure sensitive adhesivecomponent to the liquid plasticizer is at least 12.5:1.

The pressure-sensitive adhesive compositions for providing the pressuresensitive adhesive layer on the foam layer can be made using methodsknown in the art. For example, they can be made by dissolving the blockcopolymers, suitable tackifiers, any plasticizer(s), and any otheradditives including an acrylic pressure sensitive adhesive component ina suitable solvent, and coating onto a release liner or directly ontothe foam layer using conventional means (e.g., knife coating, rollcoating, gravure coating, rod coating, curtain coating, spray coating,air knife coating). In some embodiments, the pressure-sensitive adhesivecomposition of the pressure sensitive adhesive layer is prepared in asubstantially solvent-free process (i.e., the adhesive contain nogreater than about 20 wt. % solvent, in some embodiments, no greaterthan about 10 wt. % solvent and, in some embodiments, no greater thanabout 5 wt. % solvent, in some embodiments, no greater than 1 wt. %solvent, or even no greater than trace amounts of solvent (i.e.,essentially no solvent). Such substantially solvent-free processes areknown and include, e.g., compounding by calendaring or roll milling, andextruding (e.g., single. screw, twin screw, disk screw, reciprocatingsingle screw, pin barrel single screw, etc.). Commercially availableequipment such as BRABENDER or BANBURY internal mixers are alsoavailable to batch mix the adhesive compositions. After compounding, theadhesive may be coated through a die into a desired form, such as alayer of adhesive, or it may be collected for forming at a later time.In a particular embodiment the pressure sensitive adhesive compositionmay be extruded on the foam layer or may be extruded on a release linerand then subsequently laminated to the foam layer.

The pressure sensitive adhesive layer is typically applied on the foamlayer at a weight per area of between 40 and 100 g/m².

In accordance with the method of making the adhesive article, thecross-linkable rubber, for example one or more cross-linkable blockcopolymers as described above, of the pressure sensitive layer iscross-linked. In a particular embodiment, the cross-linkable rubber iscross-linked by subjecting the pressure sensitive adhesive layer on thefoam layer to e-beam irradiation. Typically, e-beam irradiation will becarried out with an acceleration voltage of between 100 and 300 keV anda dose of 2 to 9 MRad. In a particular embodiment the e-beam irradiationis focused at the interface of the pressure sensitive adhesive layer andfoam layer. In another embodiment, the focus of the e-beam may be in theproximity of the interface, for example within about 10 and 30micrometer of the interface, with the focus in the foam layer or in thepressure sensitive adhesive layer.

When the pressure sensitive adhesive composition having a cross-linkablerubber is provided on both opposite major sides of the foam layer, itwill typically be preferred to irradiate such a laminate from bothopposite major sides either sequentially of simultaneously.

In another embodiment, the pressure sensitive adhesive layer having across-linked rubber may be provided on only one of the major sides ofthe foam layer. The other major side may then be left without a furtheradhesive layer as the foam layer in accordance with the presentdisclosure will typically have useful pressure sensitive adhesivecharacteristics. In an alternative embodiment, a further adhesive layermay be provided on the major side opposite to the major side having thepressure sensitive adhesive layer with the cross-linked rubber. Suchfurther adhesive layer may include any common pressure sensitiveadhesive including acrylic pressure sensitive adhesive layers, siliconebased adhesives, polyurethane based adhesives, poly-alpha olefins andthe like.

In yet a further embodiment, a further adhesive layer provided on theopposite major side may include a heat-activatable adhesive layer. Withheat-activatable adhesive layer is meant an adhesive that requiresheating in order to develop its maximum bond strength in bonding to asubstrate. A heat-activatable adhesive may or may not have usefulpressure sensitive adhesive properties at room temperature (about 25°C.). Typically, a heat-activatable adhesive for use with the presentdisclosure will be based on a thermoplastic polymer such as for examplea film of a copolymer of ethylene and propylene, thermoplasticpolyurethane which may be tackified or not.

The adhesive articles in connection with the present disclosure can beused to bond to a substrate. Thus, the pressure sensitive adhesive layerof adhesive article is used to bond the article to a desired substrate.In a particular embodiment, such a substrate may have a low surfaceenergy, for example of less than 45 dynes/cm or less than 40 dynes/cm or35 dynes/cm or less.

The adhesive articles are particularly suitable for bonding variouscomponents including for example emblems, plastic body moldings andrubber gaskets to a body of a motor vehicle, in particular a car. Forexample, in one embodiment the adhesive article may be bonded throughits pressure sensitive adhesive having a cross-linked rubber to the bodyof a car. A plastic molding, emblem and the like may be adhered to theadhesive article on the opposite major side which may or may not containa further skin adhesive layer. Generally, the emblem, plastic molding orgasket will be first bonded to the adhesive article, and the resultingassembly may then be bonded to the motor vehicle, in particular the car.

In another embodiment, the adhesive article may be bonded on the majorside opposite to the major side having the pressure sensitive adhesivelayer comprising the cross-linked rubber to a rubber gasket. Such rubbergasket may be directly bonded to the foam layer of the adhesive articlebut is typically bonded thereto through a further skin adhesive layerthat is provided on the foam layer. In one embodiment, such a skinadhesive layer may be a pressure sensitive adhesive and in anotherembodiment the skin adhesive layer comprises a heat activatableadhesive.

Adhesive articles provided with a rubber gasket as described in theprevious paragraph can be readily applied to for example a door of a carso as to provide a door seal.

The invention will now be illustrated with reference to the followingnon-limiting examples. All parts are by weight unless otherwise stated.

EXAMPLES Test Methods

Dynamic Shear Test:

A modified version of ISO4587: 2003 was employed.

The tape to be tested was applied with its specific side to the paintedsteel substrate. To the opposite side of that tape an aluminum coupon(50 mm×25 mm×1 mm) was applied.

The bonded tape area is 1.27 cm×2.54 cm horizontally applied.

The painted steel panels employed in this test method were obtained froma supplier mentioned in a separate section below. A basic descriptionabout the paints is provided in that separate section below as well.

Paint A and paint B were cleaned by wiping with a tissue saturated inn-heptane. Paint C was cleaned by wiping with a tissue saturated with a1:1 volume mixture of water and isopropanol. For the test, the paintedsteel panel substrates were cut into coupons (50 mm×30 mm×1 mm).

The aluminum coupons were subjected to light abrasion with aScotchbrite™ no. 7447™ scrubbing pad (available from 3M Company)followed by cleaning/wiping with a tissue saturated with Methylethylketone, and finally cleaned by wiping with a tissue saturated with a 1:1volume mixture of water and isopropanol.

The assemblies were prepared by applying first the treated aluminumcoupon side the exposed tape surface side, cut into an 1.27 cm×2.54 cmarea. Then the liner is removed from the opposite specific tape areaside and the cleaned painted steel panel coupon is applied to this tapesurface, using a 6.8 kg roller over rolling the test specimen twice witha speed of 300 mm/min. After a dwell time of 20 min, 24 hrs or 72 hrsthe dynamic shear strength test was performed with 10 mm/min or 50mm/min cross-head speed. The test was repeated with 3 three repeatingtest samples and the average value was reported.

90° Peel Adhesion Test:

90° peel adhesion at 300 mm/min was measured according to FederationInternationale des Fabricants Europeens et Transformateurs d'Adhesifs etThermocollants sur Papiers et autres Supports (FINAT) test method no. 2with following exceptions:

The pressure sensitive adhesive layer of the present disclosure wereallowed to dwell on the substrates before testing for 20 min, 24 hrsand/or 72 hrs, as indicated in the table below.

The width of the tested tapes was 1.27 cm rather than 2.5 cm as calledfor by the FINAT test.

A 150 μm thick aluminium strip being anodized on one side and having awidth of 1.6 cm is applied by hand with anodized side to specific sideof the tape to be tested to form a non-extendible backing.

A 6.8 kg roller was used to apply the tape to be tested to the substraterather than 2 kg as required by the method. The 6.8 kg roller was rolledtwice over the test specimen with a speed of 300 mm/min.

Substrates employed were painted steel panels obtained from a suppliermentioned in a separate section below. A basic description about thepaints is provided in that separate section below as well. Paint A andPaint B were cleaned by wiping with a tissue saturated in n-heptane.Paint C was cleaned by wiping with a tissue saturated with a 1:1 volumemixture of water and isopropanol.

Results were reported in N/cm rather than N/2.5 cm as called for by themethod.

Static Shear Test at Elevated Temperatures:

A standard static shear test was performed at elevated temperatureaccording to Pressure Sensitive Tape Council (Chicago, Ill./USA)PSTC-107 (procedure G). The test was performed at 90° C. rather than 49°C. (120° F.) as called for by the method. The substrates employed werepainted steel panels obtained from a supplier mentioned in a separatesection below. A basic description about the paints is provided in thatseparate section below as well. Paint A and Paint B were cleaned bywiping with a tissue saturated in n-heptane. Paint C was cleaned bywiping with a tissue saturated with a 1:1 volume mixture of water andisopropanol.

The bonded sample area was 2.54 cm in the vertical direction by 1.27 cmin the width direction (rather than 1.27 cm×1.27 cm as called for by themethod). To the tape side opposite to that side which will be appliedwith its specific side to the painted substrate, a 150 μm thickaluminium strip is applied superimposing the tape area to provide ameans of a load weight as described in PSTC-7. This aluminium strip hasa width of 1.6 cm and is anodized on one side. This anodized aluminiumstrip side is to be applied first to the tape area. Then a 6.8 kg rollerwas used to apply the specific side of the tape area to be tested to thepainted substrate panel. The roller was rolled twice over the testspecimen with a speed of 300 mm/min. After a dwell time of 24 hrs thetest specimen were hung in the shear stand at elevated temperature. Theshear stand with the test specimen was placed in a forced air oven heldat the elevated temperature (90° C.) for 10 min to condition it and thenthe load of 750 g (rather than 1 kg as called for by the method) washung from the end of the aluminum strip bonded to the tape area to betested. The time to failure for the adhesive bond was recorded inminutes. After passing 10000 min of holding time the test was stopped.

Description of the Painted Metal Panels Used as Substrates in the AboveMentioned Tests:

Paint A:

1K acrylic powder coating, generation 9, automotive paint, coated onsteel plates, obtained from DuPont Performance Coatings GmbH&Co.KG,Wuppertal.

Paint B:

1K acrylic powder coating, generation 8, automotive paint, coated onsteel plates, obtained from DuPont Performance Coatings GmbH&Co.KG,Wuppertal.

Paint C:

2K clear coat, automotive paint containing nanoparticles, coated onsteel plates, obtained from PPG Industries Lacke GmbH, Ingersheim.

Materials Used in the Examples:

TABLE 1 Summary of materials Abbreviation Name Source AA Acrylic Acid BAButyl acrylate IOA Isooctyl acrylate 2-EHA 2-Ethylhexyl acrylate HDDAHexanediol diacrylate Irgacure ™ 651 2,2 dimethoxy-2-phenylacetophenoneCiba Specialty Chemicals Corp. (Tarrytown, NY) IOTG Isooctylthioglycolate Kraton ™ 1161-D SIS linear block copolymer KratonPolymers, Inc. (15% S, 19% diblock) (Houston, Texas) Santicizer ™ 1412-ethylhexyl diphenyl phosphate Ferro Co. (Bridgeport, New Jersey)Escorez ™ 1310 Aliphatic C-5 tackifying resin ExxonMobil Chemical LTD.(Southampton, Hampshire, GB) 4900 MB Black pigment having a 50/50 blendof MA Hanna Color (Suwannee, Georgia) carbon black in ethylene vinylacetate copolymer resin having a melt index of about 150 Superester ™W-115 Stabilized rosin acid ester Arakawa Chemical USA (Chicago, IL)Irganox ™ 1010 Pentaerythritol tetrakis (3-(3,5-di-tert- Ciba SpecialtyChemicals Corp. (Tarrytown, NY) butyl-4-hydroxyphenyl)propionate)Tinuvin ™ 328 2-(2-hydroxy-3,5-di-(tert)- Ciba Specialty Chemicals Corp.(Tarrytown, NY) amylphenyl)benzotriazole Regalite ™ R1125 Hydrogenatedhydrocarbon resin Eastman Chemical Co. (Kingsport, TN) Cumar ™ 130Aromatic thermoplastic resin Neville Chemical Co. (Pittsburgh, PA)Nyplast ™ 222B Naphthenic oil plasticizer Nynas Naphthenics AB(Stockholm, Sweden) K15 Hollow glassbubbles 3M Co. SurfactantFluoroaliphatic polymer 3M Co. Aerosil ™ 972 Hydrophobic fumed silicaEvonikPreparation of Acrylic Polymers:

Acrylic Polymer 1 (AP-1) was prepared by mixing 45 parts of IOA; 45parts of BA; 10 parts of AA; 0.15 part IRGACURE 651; and 0.06 part ofIOTG. Discreet film packages were formed from a packaging film (0.0635mm thick ethylene vinyl acetate copolymer film sold as VA-24 Film fromCT Film, Dallas, Tex.). The AP-I composition was sealed into the filmpackages, which measured approximately 10 centimeters (cm) by 5 cm by0.5 cm thick. While immersed in a water bath maintained between about21° C. and about 32° C., the packages were exposed to ultraviolet (UV)radiation having an intensity of about 3.5 milliwatts per squarecentimeter (mW/sq cm), and a total energy of about 1680 milliJoules persquare centimeter (mJ/sq cm) as measured in NIST units. The method offorming the packages and curing are described in Example 1 of U.S. Pat.No. 5,804,610, the subject matter of which is incorporated herein byreference in its entirety.

Acrylic Polymer 2 (AP-2) was prepared according to the procedure forAP-1, except that 85 parts of 2-EHA; 15 parts of AA; 0.15 parts ofIRGACURE 651; and 0.8 part IOTG were used. Similarly, Acrylic Polymer 3(AP-3) was prepared according to the procedure for Acrylic Polymer 1except that the composition was 95 parts of 2-EHA; 5 parts of AA; 0.15part IRGACURE 651; and 0.03 part of IOTG. AP-2 and AP-3 were placed inpackages and exposed to UV energy, according to the procedure for AP-1.

First Skin Adhesive (SA-1):

Pressure-sensitive adhesives according to the compositions shown inTable 2 were compounded using a 60 mm, co-rotating twin screw extruder(available from Berstorff), (the “first adhesive extruder”). Apolymodal, asymmetric star block copolymer (“PASBC”) was preparedaccording to U.S. Pat. No. 5,393,373, the subject matter of which ishereby incorporated by reference in its entirety. The polymer had numberaverage molecular weights of about 4,000 Dalton and about 21,500 Daltonfor the two endblocks, 127,000-147,000 Dalton for the arm, and about1,100,000 Dalton for the star measured by SEC (size exclusionchromatography) calibrated using polystyrene standards. The polystyrenecontent was between 9.5 and 11.5 percent by weight. The mole percentageof high molecular weight arms was estimated to be about 30%.

The polymodal asymmetric block copolymer and a linearstyrene-isoprene-styrene (SIS) block copolymer (KRATON 1161-D) were dryfed into the first zone of the first adhesive extruder. Using aroll-feed extruder (available from Berstorff), acrylic polymer AP-1 washeated and fed into the third zone of the first adhesive extruder.Antioxidant (IRGANOX 1010), ultraviolet light absorber (TINUVIN 328),pigmented EVA (4900 CMB) were dry fed; and (REGALITE R 1125); (CUMAR130); and (NYPLAST 222B) were melt fed in to various zones of the firstadhesive extruder.

TABLE 2 First skin adhesive composition (SA-1) Component Amount inweight percent PASBC* 31.19 Kraton 1161D 13.37 Regalite R1125 30.91Cumar 130 10.30 Nyplast 222B 7.20 Irganox 1010 1.34 Tinuvin 328 1.344900 CMB 0.38 AP-1 4 *Polymodal, asymmetric star block copolymerSecond Skin Adhesive (SA-2):

A pressure sensitive adhesive was compounded in a 60 mm, co-rotatingtwin screw extruder (available from Berstorff) (the “second adhesiveextruder”) in a similar manner as described for the first skinadhesives, except that the composition was as follows: 12.70% of thepolymodal, asymmetric star block copolymer (PASBC); 53.10% (by weight)AP-1; 23.30% tackifying resin (ESCOREZ 1310LC); 3.80% tackifying resin(SUPERESTER W115; 6.20% plasticizer (SANTICIZER 141); 0.26% antioxidant(IRGANOX 1010); 0.25% ultraviolet light absorber (TINUVIN 328) and 0.38%CMB 4900.

Double-Sided Foam Tape Samples Example A

The Foam core (FC-1) having the composition shown in Table 3 wascompounded according to the following procedure. Black pigmented EVA(4900 CMB) was dry fed in to the first zone of a 90 mm, co-rotating twinscrew extruder (the “core extruder”) (available from Berstorff,Hannover, Germany). Using a roll-feed extruder (available fromBerstorff), both acrylic polymers AP-2 and AP-3 were heated and fed intothe second zone of the core extruder. DUALITE U010-185D expandablemicrospheres (expandable microspheres having a shell compositioncontaining acrylonitrile and methacrylonitrile and a core of isopentane,available from Henkel Corporation (Gulph Mills, Pa.) were fed into theninth zone of the core extruder.

TABLE 3 Foam core composition FC-1 and properties Components ComponentsComponents Components Parts Parts By Weigh Parts By Weigh Parts By WeighBy Weigh Percent Percent (%) Percent (%) Percent (%) (%) Foam DensitiyThickness AP-3 AP-2 Microspheres Pigment (g/cm³) (mm) 91.12 4.8 3.700.38 0.53 0.7

Three-layer co-extruded tape samples were prepared by coextruding afirst skin adhesive layer, a foam core layer as the middle layer, and asecond skin adhesive layer.

The second skin adhesive was compounded in the second adhesive extruder,as described above, and fed through an outer layer of a three-layer,multi-manifold film die obtained from Cloeren Inc. (Orange, Tex.). Afoam core layer was compounded in the core extruder, as described above,and fed to the center layer of the three-layer die. A first skinadhesive was compounded in the first adhesive extruder, as describedabove, and fed to the outer layer of the three-layer die, opposite thesecond skin adhesive.

Upon exiting the die, the co-extruded layers were cast onto a siliconerelease coated casting roll. The roll was cooled with water having atemperature of about 12° C. The cooled extrudate was transferred fromthe casting roll to a 0.117 mm thick two-side silicone coatedpolyethylene release liner that was transported at the same speed as thecasting roll to the end of the web transport line. The first skinadhesive was in contact with the liner after the transfer whereas thesecond skin adhesive was open to the air. The liner had differentialrelease properties which allow the tape to be unrolled after windingwithout liner confusion. Release liners are well-known in the art, andany known release liner may be used. Typically, the release linercomprises a film or paper substrate coated with a release material.Commercially available release liners include, but are not limited to,silicone coated papers, and silicone coated films, such as polyesterfilms. Suitable release liners are also disclosed in U.S. Pat. Nos.6,835,422; 6,805,933; 6,780,484; and 6,204,350 assigned to 3M InnovativeProperties Company.

The foam core and both adhesive skins were crosslinked on-web usingelectron beam curing while supported on the liner. Two sequentialirradiation steps acting on opposite faces of the tape were employed.The first skin adhesive was irradiated through the polyethylene liner,whereas the second skin adhesive was irradiated in an open-facecondition. The electron beam units were BROADBAND curtain-type electronbeam processors (PCT Engineered Systems, LLC, Davenport, Iowa), operatedaccording the acceleration voltage and dose conditions provided in Table4.

TABLE 4 Composition of three-layer tape sample First Second skin Secondskin First skin adhesive skin adhesive adhesive (SA-2) adhesive (SA-1)(SA-1) Acceleration (SA-2) Foam Acceleration Dose Voltage Dose ExampleCore Voltage (keV) (MRad) (keV) (MRad) A FC-1 247 11.5 235 10

Example B

Into the mixture of the photopolymerizable monomers (2-EHA and AA) wasstirred 0.04% by weight of 2,2-dimethoxy-2-phenyl acetophenone(obtainable as “Irgacure” 651). This was partially polymerized toprovide a syrup about 3000 cps in viscosity by exposure to ultravioletradiation. To the syrup was added 0.20% by weight of additional“Irgacure” 651 and crosslinking agent HDDA. To this prepolymer mixturethe fillers Aerosil 972 and the glass bubbles were added and slowlymixed using a motorized stirrer equipped with an air motor. Afterdegassing and the addition of surfactant and pigments the mixture wastransferred to a frother operating at 300 rpm.

While nitrogen gas was fed into the frother, the frothed syrup wasdelivered through a tube to a knife coater between a pair oftransparent, biaxially-oriented polyethylene terephthalate films, thefacing surfaces of which had low-adhesion coatings. The compositeemerging from the knife coater was irradiated with a bank of fluorescentblack light bulbs (Sylvania F20T12BL), 90% of the emissions of whichwere between 300 and 400 nm with a maximum at 351 nm to complete thepolymerisation to a pressure sensitive adhesive foam layer. The totalexposure was 1360 mJ/cm² as measured by an EIT UV Radiometer which isspectrally responsive between 250 and 430 nm, maximum 350 nm. Thecomposite was cooled by blowing air against both films during theirradiation to keep the temperature of the films below 85° C. to avoidwrinkling of the films. The PET process liners finally are stripped anda double-sided siliconized release paper liner is laminated to one ofthe two tape surfaces to allow for the roll winding and unwinding lateron.

TABLE 5 Composition of Example B and C: Solids Pigment + Monomers RatioCrosslinker Glassbubbles + Nitrogen Example 2-EHA/AA HDDA Aerosil Flowrate flow Pressure Caliper Nr. [%] [%] [%] kg/h l/h kPa [μm] B 2-EHA/AA0.1 8.5 550 8.7 250 800 83.4%/8.0% C 2-EHA/AA = 0.1 8.5 550 8.7 250 120083.4%/8.0%Samples 1 to 8:

The following examples were generated by applying a layer of the abovementioned first skin adhesive SA-1 (which was used to make Example A)onto the surface of the foam layer of Example B, followed by an e-beamradiation process.

Several methods can be employed to apply a layer of the first skinadhesive onto the foam layer of Example B:

A) Laminating a transfer tape, obtained by hot melt coating the skinadhesive formulation onto a doublesided siliconized release carrierliner, to the foam layer (lamination force: typically 50 N per webwidth.)

B) Directly hotmelt coating onto the surface of the foam layer using aslot die.

C) Directly hotmelt coating onto the surface of the foam layer via anextrusion line and using a rotary rod die.

D) Directly coating of a solvent based formulation of the skin adhesiveonto the foam layer, followed by an oven drying process.

Various e-beam radiation curing conditions were employed (Oxygen levelin the e-beam chamber: always below 50 ppm).

TABLE 6 Process conditions for E-beam radiation Acceleration Beam LineMethod of post e- e-beam dosage Voltage Current Speed beam radiation[MRad] [keV] [mAmpere] [m/min] EB1 6 190 1.9 3 EB2 6 220 2.2 3 EB3 8 2102.9 3 EB4 6 210 2.2 3 EB5 4 210 1.5 3 EB6 2 210 1.2 5The following table summarizes the constructions of the various samples:

TABLE 7 Coat Process weight method of Temperature Method of Type of ofskin making the of the Temperature post e- skin layer respectiveextrusion line of the coating beam Sample Nr. adhesive [g/m²] Foam Coresample [° C.] die [° C.] treatment Sample 1 SA-1 60 Example B A 200 175EB1 Sample 2 SA-1 60 Example B A 175 175 EB2 Sample 3 SA-1 85 Example BC 200 200 EB3 Sample 4 SA-1 85 Example B C 200 200 EB4 Sample 5 SA-1 85Example B C 200 200 EB5 Sample 6 SA-1 85 Example B C 200 200 EB6 Sample7 SA-1 85 Example B D Oven drying Oven drying EB4 Sample 8 SA-1 85Example C B None 208 EB6

The samples summarized in table 7 were adhered with the pressuresensitive adhesive skin layer to the substrate as indicated in thetables below which summarize the results obtained using the test methodsset out above.

Test Results:

TABLE 8 Dynamic Shear Test Results: Dynamic Shear Type of Jaw SpeedStrength Failure Example # Substrate Dwell Time [mm/min] [N/cm²] ModeSample1 Paint C 72 hrs. 50 126 FS/pop Sample 2 Paint C 72 hrs. 50 128pop Example A Paint C 72 hrs 50 74 FS Example B Paint C 72 hrs 50 89 popSample 1 Paint C 24 hrs 50 102 FS/2B Sample 2 Paint C 24 hrs 50 115FS/2B Example A Paint C 24 hrs 50 66 FS Example B Paint C 24 hrs 50 81pop Sample 4 Paint A 24 hrs 10 100 FS Sample 5 Paint A 24 hrs 10 97 FSSample 6 Paint A 24 hrs 10 86 FS Sample 7 Paint A 24 hrs 10 93 FS Sample8 Paint A 24 hrs 10 84 2B/FS Example A Paint A 24 hrs 10 45 FS Example BPaint A 24 hrs 10 43 pop Example C Paint A 24 hrs 10 34 pop

TABLE 9 90° Peel Adhesion Test Results: Average Type of Dwell Jaw Speedpeel force Failure Example # Substrate Time [mm/min] [N/cm] Mode Sample1 Paint C 72 hrs. 300 41 pop Sample 2 Paint C 72 hrs. 300 43 pop ExampleA Paint C 72 hrs 300 45 FS Example B Paint C 72 hrs. 300 14 pop Sample 1Paint C 24 hrs 300 38 Pop sh Sample 2 Paint C 24 hrs 300 33 Pop smoothExample A Paint C 24 hrs 300 43 FS Example B Paint C 24 hrs 300 11 popSample 4 Paint A 24 hrs 300 33 pop Sample 5 Paint A 24 hrs 300 35 PopSample 6 Paint A 24 hrs 300 39 pop Sample 7 Paint A 24 hrs 300 20 popSample 8 Paint A 24 hrs 300 41 pop Example A Paint A 24 hrs 300 40 FSExample B Paint A 24 hrs 300 7 pop Example C Paint A 24 hrs 300 8 popFailure modes: FS = foam split Pop = pop off panel 2B = 2-bond failuremode FS/2B = mixed failure mode of foam split and 2-bond failure modePop sh = shocky pop of panel

TABLE 10 Results of Static Shear Test @ 90° C. Type of Holding Time LoadFailure Example # Substrate Dwell Time [min] [g] Mode Sample 1 Paint C24 hrs. >10000 750 none Sample 2 Paint C 24 hrs. >10000 750 none ExampleA Paint C 24 hrs <1900 750 FS Example B Paint C 24 hrs >10000 750 noneSample 3 Paint A 24 hrs 2 × >10000 750 none 1 × 7211  2B Sample 4 PaintA 24 hrs 2 × >10000 750 none 1 × 641   2B Sample 5 Paint A 24 hrs 2× >10000 750 none 1 × 1493  2B Sample 6 Paint A 24 hrs <169 750 2BSample 8 Paint A 24 hrs 7 1000 2B Example A Paint A 24 hrs 121 1000 2BExample A Paint B 24 hrs <1045 750 FS/pop Example B Paint B 24hrs >10000 750 none Example C Paint A 24 hrs >10000 1000 none

The invention claimed is:
 1. Adhesive article comprising a foam layerhaving first and second major sides and a pressure sensitive adhesivelayer associated with at least one of the major sides for the foamlayer, said pressure sensitive adhesive layer comprising a cross-linkedrubber and wherein the foam layer comprises an acrylic polymerobtainable by polymerization of a polymerizable composition comprisingone or more alkyl acrylates having an average of 3 to 14 carbon atoms inthe alkyl groups, one or more polar monomers and one or moremulti-functional monomers having at least two free radical polymerizablegroups, a fluoroaliphatic surfactant; and at least 0.20 wt % of a crosslinking agent, wherein said polymerizable composition comprises 83 to97% by weight of said alkyl acrylates, 3 to 16% by weight of said polarmonomers and 0.01 to 1% by weight of said multi-functional monomers. 2.Adhesive article according to claim 1 wherein said pressure sensitiveadhesive layer comprises an acrylic pressure sensitive adhesivecomponent.
 3. Adhesive article according to claim 2 wherein said acrylicpressure sensitive adhesive component comprises an acrylic polymerhaving repeating units derived from one or more alkyl acrylates having 3to 14 carbon atoms in the alkyl group and one or more polar monomers. 4.Adhesive article according to claim 1 wherein cross-linked rubbercomprises a cross-linked block copolymer having a rubbery block and aglassy block.
 5. Adhesive article according to claim 4 wherein saidrubbery block comprises a first polymerized conjugated diene, ahydrogenated derivative thereof, or combinations thereof and whereinsaid glassy block comprises a monovinyl aromatic monomer.
 6. Adhesivearticle according to claim 1 wherein each of said first and second majorside of said adhesive article have associated with them said pressuresensitive adhesive layer.
 7. Adhesive article according to claim 1wherein said adhesive article has said pressure sensitive adhesive layerassociated with said first major side and wherein said second major sidedoes not have an adhesive layer associated with it.
 8. Adhesive articleaccording to claim 1 wherein said adhesive article has said pressuresensitive adhesive layer associated with said first major side andwherein said second major side has a further adhesive layer associatedwith it.
 9. Adhesive article according to claim 8 wherein said furtheradhesive layer comprises a pressure sensitive adhesive component or aheat activatable adhesive component.
 10. Method of making an adhesivearticle as claimed in claim 1 comprising: making a foam layer havingfirst and second major sides by (a) providing a polymerizablecomposition comprising one or more alkyl acrylates having an average of3 to 14 carbon atoms in the alkyl groups, one or more polar monomers andone or more multi-functional monomers having at least two free radicalpolymerizable groups and a fluoroaliphatic surfactant, (b) frothing saidpolymerizable composition and (c) polymerizing said polymerizablecomposition; (ii) applying a pressure sensitive adhesive compositioncomprising a cross-linkable rubber on one or both of said first andsecond major sides of said foam layer so as to form a pressure sensitiveadhesive layer; and (iii) cross-linking said cross-linkable rubber. 11.Method according to claim 10 wherein said cross-linking comprisesexposing said cross-linkable rubber to e-beam radiation.
 12. Use of anadhesive article according to claim 1 comprising adhering said adhesivearticle to a substrate through said pressure sensitive adhesive layer.